Dynamoelectric brush



United States Patent Ofifice 3,042,629 Patented July 3, 1962 3,042,629 DYNAMQELECTRIC BRUSH Paul Smisko, St. Marys, Pa., assignor to Stackpole Carbon Company, St. Marys, Pa., a corporation of Pennsylvania N Drawing. Filed July 11, 1960, Ser. No. 41,738 5 Claims. (Cl. 252-507) This invention relates to carbon brushes for electrical apparatus such as motors, generators and the like.

It is well known in the electric equipment arts that conditions of operation at high altitude are quite severe and require special brushes as Well as other expedients to attain satisfactory wear characteristics and life in such apparatus. Brushes at high altitude conditions appear to wear by dusting and they then disintegrate with great rapidity.

It is, therefore, an object of the present invention to provide novel brushes that are of particular usefulness for use in electrical equipment operating at high altitudes.

This and other objects are attained in accordance with my invention by incorporating in a carbon brush a material containing zirconium and chlorine in about a 1:1 atomic ratio. For purposes of brevity, this material can be referred to as zirconium monochloride. The zirconium monochloride can be mixed with carbon and a brush is then formed therefrom, or can be incorporated in a brush after it is formed as by packing it in holes drilled in the wearing surface of the brush. Tests on the resulting products have shown that immediate protection against rapid wear at high altitudes as well as extended sea level operating life are attained in consequence of this practice.

The zirconium monochloride. is commercially available and is obtained in the electrolysis of molten chloride electrolytes using a zirconium anode. The resulting product is in fiake form, is insoluble in dilute acids and has the empirical formula ZrCl. This material shows that it has both metallic and ionic bonds in a single lattice. density is on the order of 3.90 to 4.00. Based on the weight of the brush containing it, the zirconium and chloride material normally is used in amounts of 1 to 30 percent and preferably itis within the range of about 7 to 22 percent.

The invention will be described further in conjunction Its to serve as a brush by pressing it into a compact having Percent Hf 0.01 Ti 0.001 Mn 0.01 Fe 0.001 Si 0.001

An amount of the material that came to about 14.6 percent of the brush weight was used. These flakes were tamped in the hole using a small rod as a hammer.

Brushes made in the foregoing manner were tested in both a bell jar and thenon slip rings. The bell jar was evacuated to simulate an altitude of 60,000 ft. Immediate protection against undue wear was provided. In sea level tests of the brushes placed against slip rings, brushes prepared as just described, after 500 hours of testing, showed a Wear of 0.07 mil per hour while the copper ring had a 0.002" wear per thousand hours.

From the foregoing discussion and data, it is evident that this invention provides a unique'brush that can be used successfully in various electrical apparatus that require a current carrying brush, with the result of obtaining good protection against dusting and wear at high altitudes and very little slip ring or brush wear at sea level. It may be noted that these results have been achieved without the necessity of applying expensive treating methods in preparing the brushes or in making any change in the manner of using the resulting brushes.

It will be apparent that modifications of the invention can be made. For example, the added material can be disposed in slots across portions of the contact face of the brush, or can be included therein in any other desirable manner. It should also be apparent that as used herein, the term carbon is intended to cover all forms of carbon, and includes graphite as well as metal-graphite mixtures.

According to the provisions of the patent statutes, I have explained the principle of my invention and have described what I now consider to represent its best embodiment.- However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

l. A brush for current carrying use in conjunction with electrical apparatus composed of: carbon and zirconium monochloride, said zirconium monochloride being present in an amount within the range of about 1 to 30 weight percent based on the resulting brush.

2. A brush in accordance with claim 1 wherein said zirconium monochloride is present within the range of about 7 to 22 weight percent.

3. A brush in accordance with claim 1 wherein said zirconium monochloride is present in an amount of about 15 weight percent.

4. A current carrying carbon brush for use in electrical apparatus containing zirconium monochloride exposed at its Wearing surface, said zirconium monochloride being present in an amount of about 1 to 30 weight percent based on the brush.

5. A brush in accordance with claim 4 wherein said zirconium'monochloride is present in an amount of about 7to 22 weight percent.

References Cited in the file of this patent UNITED STATES PATENTS 2,414,543 Moberly Jan. 21, 1947 

1. A BRUSH FOR CURRENT CARRYING USE IN CONJUNCTION WITH ELECTRICAL APPARATUS COMPOSED OF CARBON AND ZIRCONIUM MONOCHLORIDE, SAID ZIRCONIUM MONOCHLORIDE BEING PRESENT IN AN AMOUNT WITHIN THE RANGE OF ABOUT 1 TO 30 WEIGHT PERCENT BASED ON THE RESULTING BRUSH. 